Hello everyone. I want to buy one Oakley Aro5 helmet. I wanted to buy Katusha alpecin aro5 ,because that red colour is HOT, but only small size in stock. So, dimension data is the only option now, but only medium size in stock. Will medium size fit perfectly? I have never used oakley helmets before, so if anyone has any idea about oakley aro series helmets. Please share some suggestions.